1. Field of the Invention
This invention relates to a magnetic disc apparatus and, more particularly, to a thin type of magnetic disc apparatus using a magnetic disk with a small diameter.
2. Description of the Related Art
Not only general-purpose computers and workstations but also personal computers are now equipped with magnetic disc apparatus. As lower-price personal computers have come into wide use, the price of magnetic disc apparatus has fallen remarkably. To offset the lower prices, magnetic recording densities are being increased and the number of disks and heads on magnetic disc apparatus are being reduced to reduce costs. As a result, the storage capacity per unit magnetic disc apparatus has increased.
In this context, the capacities of the magnetic disks used as recording media used in personal computers have been increased to a sufficient degree. On the other hand, the increased capacities of magnetic disc apparatus have allowed huge amounts of information such as motion picture and music data to be handled, so attempts have begun to be made to use magnetic disc apparatus in household electrical information appliances other than personal computers. In particular, demands for diverse applications of magnetic disc apparatus are beginning to grow, as seen in such trends as the use of magnetic disc apparatus to construct databases with massive amounts of information, and the tendency of individual persons to carry these massive amounts of information with them for use at any time and place.
As the magnetic disc apparatus used by individual persons to carry massive amounts of information with them as mentioned above, a magnetic disc apparatus smaller and thinner than the 2.5-inch or 3.5-inch magnetic disc apparatus used in current personal computers is required.
The smaller and thinner size needed for this purpose is achieved in a portable external magnetic disc apparatus as described in JP-A-180426/1997. This portable external magnetic disc apparatus uses a magnetic disk with smaller diameter for lower power consumption and higher portability.
FIG. 8 is a perspective view of a 2.5-inch magnetic disc apparatus mounted on current notebook personal computers. The magnetic disc apparatus shown in FIG. 8 comprises a case 405 and a cover (omitted in FIG. 8) that hermetically enclose the inside; a spindle motor is secured to the case 405. A magnetic disk 400 is attached to the spindle motor by a clamp 406, with a spacer disposed between them. A carriage is provided on the case 405. This carriage has a suspension 402 tipped with a magnetic head 411 for reading and writing information on the magnetic disc 400. In addition, the carriage has a radial degree of freedom with respect to the magnetic disc 400, provided by a pivot 412, and can be driven to a given position on the surface of the magnetic disc 400 by a voice coil motor (VCM) 407 attached to the case 405.
Signals from the magnetic head 411 are transmitted through a flexible printed circuit (FPC) 403 to a pre-amplifier integrated circuit 404 where they are amplified. A further connector (not shown in FIG. 8) conducts the signals to a printed circuit board (PCB) 408 where they are processed by electronic components 409, and the processed signals are transmitted by an external connector 410 to the outside.
The portable compact magnetic disc apparatus, as mentioned above, also has this basic structure, except that it is thinner than the 2.5-inch magnetic disc apparatus. Current 2.5-inch magnetic disc apparatus has a device thickness of 9.5 mm, while the portable compact magnetic disc apparatus has a minimum device thickness of 5.0 mm.
In 2.5-inch magnetic disc apparatus with a device thickness of 9.5 mm, the thickness of the printed circuit board is about 0.6 mm, the ratio of which to the device thickness is about 6.3%. In a portable compact magnetic disc apparatus with a device thickness of 5 mm, the thickness of the printed circuit board is about 0.4 mm, the ratio of which to the device thickness is about 8.0%. It is clear that the portable magnetic disc apparatus has a higher ratio of the board thickness of the printed circuit board 408 to the device thickness as described above.
The prior art includes a structure, disclosed by JP-A-111290/1992, comprising a layer of insulative material that is provided on the internal surface of a case or a cover, and a circuit pattern that is formed on the layer of insulative material for mounting electronic components, thereby reducing the thickness of a magnetic disc apparatus. In another structure, disclosed by JP-A-176186/1995, a layout of electronic components and connectors are electrically connected to a circuit board, a spindle motor and an actuator are secured to the circuit board, and the circuit board is screwed to a cover, thereby reducing the thickness of a magnetic disc apparatus. The art described in JP-A-115590/1996 provides a structure comprising a circuit board with a hole, and a metal base plate that occupies the hole; the metal base plate has holes for securing the spindle motor and actuator, and for components forming connections between the case and the circuit board, thereby reducing the number of components.
Flexible printed circuit connector joining methods used in current magnetic disc apparatus include a structure disclosed in JP-A-106761/1996 and the structure shown in FIG. 9. FIG. 9 is an expanded cross-sectional view through line Axe2x80x94A of an FPC-PCB connector joint part transmitting signals from a magnetic head in the current compact magnetic disc apparatus shown in FIG. 8.
In FIG. 9, the pre-amplifier integrated circuit 500 is soldered to the upper surface of a flexible printed circuit 502 that is connected to the signal-flow path from the magnetic head and supported by a flexible printed circuit plate 501. The flexible printed circuit 502 bends around to the opposite side of the flexible printed circuit plate 501 and is there connected to a flexible printed circuit connector 505. The flexible printed circuit connector 505 transmits magnetic head signals through the case 506 to a printed circuit board 503 outside the case 506. The flexible printed circuit connector 505 makes the signal connections by being pressed against a solder joint part 504 on the printed circuit board 503. As shown in FIG. 9, the case 506 has through-holes for the flexible printed circuit connector 505, around which a packing or sealing substance is used to form a hermetic seal.
For magnetic disc apparatus that uses a flexible printed circuit to provide power and transmit control signals to a spindle motor, the prior art disclosed by JP-A-185371/1999 uses a connector that clamps around the flexible printed circuit, to which it is connected by clamping pressure.
Therefore, if a basic structure similar to that of current magnetic disc apparatus is adopted, it is necessary to reduce the thickness of the case and the cover still further to achieve the thin size suitable for portable magnetic disc apparatus. The case, however, has a spindle motor, a carriage, and a voice coil motor attached to it, so it must maintain the stiffness needed to support these system components. Therefore, if the case thickness is reduced, it is possible that the case may be unable to maintain the stiffness and may allow vibration which, when transmitted to the outside, causes noise problems. Another possibility is that the cover may be deformed by external forces, and may come in contact with the magnetic disc.
For the printed circuit board, if the board thickness is reduced, stress concentration at the points where electronic components are soldered onto the printed circuit board may warp the printed circuit board. In that case, the problem of faulty connections arises at the place where the connector that transmits signals from the magnetic head to the printed circuit board is joined to the printed circuit board.
In the current structure, described in JP-A-111290/1992 and other patent documents, comprising an integrated molding instead of a printed circuit board separate form the case, the case must have a separate part for attachment of the interface connector, which is a stumbling block for achieving thin size of the apparatus. In the art described in the document above, it is specified that a printed circuit board having electronic components mounted be provided inside the case, so the structure requires adding a separate interface connector for connection from the connector ends of the printed circuit board inside the case to the outside. The drawing attached to this patent document shows an interface part 25 as a separate structural element of a printed circuit board inside the case. Therefore, it is necessary to provide a connector mechanism for interconnecting the printed circuit board and the interface part, which mechanism becomes a possible source of faulty connections.
It is therefore a first object of the present invention to provide a thinner type of magnetic disc apparatus by placing electrical wiring patterns on the case, thereby implementing the functions of a printed circuit board corresponding to those of the prior art, instead of providing a printed circuit board as a discrete part, separate from the case, as in the prior art, and, regarding the interface part providing external connections for the magnetic disc apparatus, by providing printed wiring on the case to implement the interface function, while maintaining required stiffness of the case.
If the basic structure of current magnetic disc apparatus is used to achieve smaller and thinner size for portable magnetic disc apparatus, there is a possibility that it may become impossible to provide adequate room to connect a flexible printed circuit connector to electrical wiring inside the magnetic disc apparatus. If there is not adequate room, redesigning is necessary to make the connector that has been used in the current magnetic disc apparatus thinner and more compact. In this case, custom design is required every time the outer dimensions of the magnetic disc apparatus are changed, resulting in increased cost. At the same time, since making a connector smaller and thinner reduces the area of contact with the flexible printed circuit, thus reducing the pressing force on the flexible printed circuit, there is a possibility that the connector may become more easily disconnected, causing faulty connections.
It is therefore a second object of the present invention to make magnetic disc apparatus smaller and thinner and more reliable by directly connecting the end part of the flexible printed circuit in the magnetic disc apparatus to the ends of the electrical wiring in the case.
In order to solve the problems described above, the present invention provides the following structures.
Magnetic disc apparatus comprising: a magnetic disk; a spindle motor that rotationally actuates the magnetic disk; a magnetic head that records and reproduces information on the magnetic disk; a carriage having the magnetic head at its tip; a voice control motor that drives the carriage; electronic components for processing signals from the magnetic head; a case on which these components are mounted; electrical wiring that interconnects the magnetic head and the electronic components or interconnects the electronic components, or both, and is integrated with the case; and an interface connector part, also integrated with the case, that transmits signals processed by the electronic components to the outside.
Magnetic disc apparatus comprising: a magnetic disk; a spindle motor that rotationally actuates the magnetic disk; a magnetic head that records and reproduces information on the magnetic disk; a carriage having the magnetic head at its tip; a voice coil motor that drives the carriage; electronic components for processing signals from the magnetic head; a case on which these components are mounted; electrical wiring that interconnects the magnetic head and the electronic components or interconnects the electronic components, or both, and is plated onto the inner bottom surface of the case; and an interface connecting part plated onto the outer bottom surface of the case that is connected to the electrical wiring plated onto the inner bottom and side-wall surfaces of the case.
Magnetic disc apparatus, wherein: the case is made of an insulative resin material and is formed as a single unit;
the electrical wiring that connects the electronic components in the magnetic disc apparatus is plated onto the inner bottom and side-wall surfaces of the case and is thereby integrated with the case; and the interface connecting part that provides external connections for the magnetic disc apparatus is plated onto the outer bottom surface of the case and is integrated with the case; thus the case serves as a structural element also offering an interface function, capable of contributing to still thinner size and stabilized operation and providing adequate fitness-for-use regarding vibration characteristics and stiffness as a product.